Am.  J  our.  Pliarm.  \ 
February,  1906.  / 
Japanese  Lac. 
55 
I  have  found  that  his  urushic  acid  consisted  of  at  least  four  sub- 
stances, one  of  which  is  the  poisonous  principle  and  is  non-volatile. 
Also  that  the  gum  and  diastatic  matter  are  inseparable.  The  vola- 
tile portion,  obtained  by  passing  steam  through  the  lac,  consisted 
of  acetic  acid  and  a  small  quantity  of  the  resinous  acid,  which  was 
evidently  carried  over  with  the  steam,  but  on  removal  from  the  dis- 
tillate by  shaking  with  ether  and  then  evaporating  was  not  volatile 
or  poisonous.    The  distillate  also  contained  acetic  acid. 
The  resinous  substances  were  removed  from  the  other  constitu- 
ents by  dissolving  in  alcohol  and  recovering  the  alcohol  by  distilla- 
tion. 
Separation  by  Lead  Acetate. — Lead  acetate  was  added  to  a  portion 
of  the  alcoholic  residue  as  long  as  a  precipitate  was  formed.  The 
precipitate,  which  was  of  a  light-gray  color,  was  washed  with  alcohol, 
mixed  with  fresh  alcohol,  decomposed  with  sulphuric  acid,  and  the 
excess  of  acid  removed  with  lead  carbonate.  On  evaporating  the 
alcohol  a  brown  oily  residue  was  obtained,  which  was  somewhat 
darker  than  the  original  alcoholic  residue,  but  otherwise  similar. 
To  the  filtrate  from  the  lead  acetate  precipitate,  solution  of  lead 
subacetate  was  added  as  long  as  a  precipitate  was  formed.  The  pre- 
cipitate was  of  a  gray  color,  but  lighter  than  that  obtained  by  lead 
acetate.  On  decomposing  the  precipitate  as  above,  an  oily  residue 
was  obtained,  which  was  also  lighter  than  that  obtained  from  lead, 
acetate. 
The  filtrate  from  the  subacetate  precipitate  was  still  of  a  brownish 
color.  The  excess  of  lead  was  removed  by  sulphuric  acid,  and  the 
excess  of  acid  removed  by  lead  carbonate  and  filtering.  The  filtrate 
was  readily  precipitated  by  lead  acetate  or  subacetate.  By  repeated 
experiments  with  the  original  alcoholic  solution  it  was  found  that 
by  precipitation  with  lead  acetate  and  removing  the  lead  and  acid 
from  the  filtrate,  adding  more  lead  acetate,  and  repeating  this  oper- 
ation until  all  of  the  resinous  substance  was  precipitated,  and  finally 
decomposing  the  separate  precipitates,  that  a  series  of  oily  residues 
could  be  obtained,  gradually  diminishing  in  quantity  and  increasing 
in  fluidity,  and  becoming  a  shade  lighter  in  color  than  the  preced- 
ing. Lead  subacetate  is  a  better  precipitant  than  lead  acetate.  The 
acetic  acid  liberated  evidently  aids  in  preventing  complete  precipi- 
tation. The  fact  that  the  fractions  decrease  in  color  and  viscosity, 
and  that  only  the  last  fractions  were  poisonous,  indicates  that  the 
